激光选区熔化成形Al–Mg–Sc–Zr合金孔隙缺陷对疲劳寿命的影响  

Effects of Pore Defects in Al−Mg−Sc−Zr Alloy Formed by Selective Laser Melting on Its Fatigue Life

作　　者：陈琨[1] 冯振宇[1] 马佳威 张宏宇 陈向明[2] CHEN Kun;FENG Zhenyu;MA Jiawei;ZHANG Hongyu;CHEN Xiangming(Civil Aviation University of China,Tianjin 300300,China;Aircraft Strength Research Institute of China,Xi’an 710065,China)

机构地区：[1]中国民航大学,天津300300 [2]中国飞机强度研究所,西安710065

出　　处：《航空制造技术》2024年第22期102-109,共8页Aeronautical Manufacturing Technology

基　　金：国家重点研发项目(2018YFB1106300)。

摘　　要：为研究激光增材制造铝合金孔隙缺陷特征及孔隙缺陷对疲劳性能的影响,基于激光选区熔化(Selective laser melting,SLM)技术成形了Al–Mg–Sc–Zr合金疲劳试样,利用X射线计算机断层扫描(X-ray computed tomography,X-CT)对疲劳试样内部孔隙缺陷的三维特征进行表征,对孔隙缺陷的数量、尺寸和形貌特征进行统计分析,利用疲劳试验测试了合金的疲劳性能,并对疲劳断口形貌进行观察。研究结果表明,孔隙缺陷主要为气孔和未熔合,其中未熔合缺陷的尺寸大、形状不规则,且多为扁平的层间未熔合缺陷。疲劳试样的孔隙率分布在0.004%~0.102%,大尺寸孔隙缺陷(等效直径>100μm)占全部孔隙缺陷的0.58%,孔隙缺陷的最大等效直径为188μm。孔隙缺陷的球形度集中在0.2~0.6,大尺寸孔隙缺陷的球形度均小于0.4。疲劳断口显示疲劳裂纹源均萌生于表面的未熔合缺陷处,且裂纹源缺陷的特征尺寸越大,试样的疲劳寿命越低。Al–Mg–Sc–Zr fatigue samples were formed by selective laser melting to study the characteristics of pore defects and effect of pore defects on fatigue properties of aluminum alloy by laser additive manufacturing.The threedimensional characteristics of pore defects in fatigue samples were characterized by X-ray computed tomography(X-CT),and the number,size and morphology of pore defects were statistically analyzed.The fatigue properties of alloy were tested by fatigue test and fatigue fracture morphology was observed.The results show that pore defects mainly comprise of porosity and lack of fusion(LOF),in which,the LOF defects are large in size,irregular in shape and mostly flat interlayer unfused defects.The porosity of fatigue samples ranges from 0.004%to 0.102%;the large-size pore defects(with an equivalent diameter>100μm)account for 0.58%of the total pore defects;the maximum equivalent diameter is 188μm.The degree of sphericity(DOS)of pore defects is between 0.2 and 0.6 with DOS of large-size pore defects less than 0.4.Fatigue fracture morphology shows that the fatigue cracks originated from LOF defects of the sample surface,moreover,the larger the feature size of the crack source defects,the lower the fatigue life of the sample.

关 键 词：激光选区熔化(SLM) X射线计算机断层扫描(X-CT) 孔隙缺陷 疲劳性能 断口形貌 

分 类 号：TG665[金属学及工艺—金属切削加工及机床] TG146.21[一般工业技术—材料科学与工程]